1. Field of the Invention
This disclosure relates to a Session Initiation Protocol (SIP) based session service, and to a method and terminal for processing or handling media data remaining in a client (i.e., client terminal) having a talk burst (i.e., granted flow, media burst) to be revoked.
2. Discussion of the Related Art
In wireless communications, SIP denotes a signaling protocol which defines a procedure in which terminals desiring to communicate each other identify and find their locations, and establish, release or change multimedia service sessions therebetween. Services based on the SIP (i.e., SIP based services) have a request/response structure of controlling generation, modification and termination of multimedia service sessions. Also, the SIP based services provide services by using a SIP Uniform Resource Locator (URL), which is similar to an email address, without regard to IP (Internet Protocol) addresses so as to enable identification of each user.
A Push-To (PT) service may be one of the SIP based session services. The PT service, which is intended to provide rapid communications for service providers and consumers over a mobile communications network, is a communication service in which one client having a talk burst or a transmit permission (i.e., permission to send a talk burst or media burst) among many clients having a session established therebetween via a server transmits media data including voice data or image data, and the rest of clients participating in the session receives the media data. The PT service can typically be a Push-to-talk Over Cellular (PoC) service for transmission of voice (audio) data to provide call services, a Push-To-View (PTV) service for transmission of moving picture (video) data, or a Push-To-Data (PTD) service for transmission of various data. The PT service can transmit voice data, image data or media data to a single recipient (1-to-1) or to groups of recipients as in a group chat session (1-to-many).
A PT service system may include PT clients (i.e., client terminals) for requesting a PT service, and a server for controlling the transmission of voice and data between PT clients to implement various types of PT services and the transmission of talk burst using a Talk Burst Control Protocol (TBCP).
The PT clients may transmit media data only after obtaining a talk burst or transmit permission (just referred to as ‘talk burst’ hereafter) for PT services. The PT clients may obtain and return (release) the talk burst through a PT server.
In order to control the talk burst, the PT clients and the PT server exchange talk burst control protocol (TBCP) messages or media burst control protocol (MBCP) messages.
The TBCP messages may include a Talk Burst Request message (i.e., TB request) which allows PT clients to request a talk burst, a Talk Burst Revoke message (i.e., TB Revoke) which the PT server to revoke (or reject) a talk burst that has been obtained by a certain PT client, or a Talk Burst Release message (i.e., TB Release) which a PT client to return (release) a talk burst granted thereto to the PT server.
A PT client completely or unconditionally transmits remained media data in a buffer (i.e., remaining buffered media data) to the PT server after the PT client, which transmits media data by obtaining a talk burst, receives a TBCP TB Revoke message (TB Revoke). And then, the PT server does not transmit the media data to a receiving PT client, rather discards the media data, of the PT client that a talk burst has been revoked.
Thus, in the PT system, since the transmitting PT client, which received the TB Revoke message, transmits all remaining buffered media data unconditionally, the PT server should unnecessarily perform the process of discarding the remaining buffered media data. In addition, the transmitting PT client transmits the media data which is to be discarded by the PT server without being transmitted to the receiving PT client by using radio resources (e.g., air bandwidth), which causes an unwanted consumption of the radio resources.
Also, in the PT system, the transmitting PT client, which received the TB Revoke message, may completely discard the remaining buffered media data. Thus, the user of the receiving PT client can not expect or prepare a sudden termination of the data transmission if the transmitting PT client completely discards the remaining buffered media data. This may cause a degradation of service quality as well.
To address such drawbacks, the features and embodiments described hereafter provide a method and terminal for processing media data for a SIP based session service in which a transmitting client having a talk burst to be revoked checks a talk burst revoke reason to selectively perform for transmission or discard of media data in a remaining buffer.